Duchenne/Becker muscular dystrophy (DBMD) represents a spectrum of X-linked disorders that result from mutations in the dystrophin gene. Due to the large size of this gene, there is a high new mutation rate making eradication of DBMD unlikely. Comprehensive, population-based surveillance along with long-term follow-up of individuals with DBMD is needed to characterize the occurrence of this disorder and its complications and to evaluate methods of delivery of health care, specific medical and surgical interventions and psychosocial impact for affected individuals and their families. In 2002, the Iowa Registry for Congenital and Inherited Disorders (IRCID) was one of four charter awardees for the Muscular Dystrophy Surveillance, Tracking and Research Network (MD STARnet). As an MD STARnet site, we successfully integrated clinical, programmatic and referral resources provided by relevant stakeholders in Iowa with the resources of the IRCID to establish a statewide infrastructure for DBMD surveillance and to implement long-term follow-up of individuals with DBMD and their families. We also conducted a needs assessment among Iowa families to better understand the impact DBMD has on individuals and their families and to identify gaps in resources and barriers to accessing resources. In addition, we established and maintained the MD STARnet Data Coordination Center (DCC) for the Centers for Disease Control and Prevention (CDC) and participating sites. For the current agreement, we propose to successfully continue as an MD STARnet site and the MD STARnet DCC to: 1) generate population-based prevalence and incidence rates for DBMD in the United States with particular attention to differences in rates over time and by race/ethnicity;2) identify the early signs and symptoms of DBMD to facilitate early diagnosis;3) describe the medical and social services received and quality of life of families of patients with DBMD and whether these vary by race/ethnicity and socioeconomic status;and 4) investigate factors that may impact the severity or course of DBMD including medical management and genetic and environmental factors. Using this population-based approach, we will gain increased understanding of the epidemiology of this disorder and its complications, which will allow for development of improved guidelines for care for individuals with DBMD.